The Volumes 1 and 2 were published by the IChO International Information Centre in Bratislava (Slovakia) on the occasion n of the 40th anniversary of this international competition.

Not less than 318theoretical and 96 practical competition problems were set in the IChO during the fourty-five years of its existence. In the elaboration of this publication the editor had to face certain difficulties because the aim was not only make use of past recordings but also to give them such a form that they may be used in practice and further chemical education. Consequently, it was necessary to make some correction in order to unify the form of the problems. However, they did not concern the contents and language of the problems.

Unfortunately, the authors of the particular competition problems are not known since due the procedure of the creation of the IChO competition problems, it is impossible to assign any author's name to a particular problem. Thus, responsibility for the scientific content and language of the problems lies exclusively with the organizers of the particular International Chemistry Olympiads.